Strobe device

ABSTRACT

A compact strobe device includes the following components: a flash discharge tube having an anode and a cathode; a conductive reflector storing a part of the flash discharge tube; a trigger coil having a hollow core, and a primary winding and a secondary winding around the core; and a conductor connecting the secondary winding of the trigger coil and the reflector. The trigger coil has an end of the flash discharge tube inserted into the core, and includes at an end thereof adjacent to the reflector, a secondary terminal connected to the secondary winding. The reflector has a bottom in contact with the outer peripheral surface of the flash discharge tube, the outer peripheral surface covering at least the region extending from the anode to the cathode. The conductor has a first contact portion in contact with the secondary terminal of the trigger coil, and a second contact portion in contact with the bottom of the reflector.

TECHNICAL FIELD

The present invention relates to a strobe device used for takingpictures or other purposes.

BACKGROUND ART

Conventional well-known strobe devices include the following components:a flash discharge tube having an anode on one side and a cathode on theother side; a reflector storing a part of the flash discharge tube; anda trigger coil having a cylindrical core and primary winding andsecondary winding wound around the core.

In the above strobe devices, the trigger coil is disposed near thereflector, and the trigger coil has a secondary terminal (outputterminal), which is in contact with the reflector (see, for example,Patent Literatures 1 and 2). According to these Patent Literatures, thisconfiguration eliminates the need to provide a lead wire connecting thereflector and the trigger coil, thereby eliminating illumination failuredue to the imperfect contact of the lead wire.

In the strobe device of Patent Literature 1, the trigger coil isdisposed behind the reflector, whereas in the strobe device of PatentLiterature 2, the trigger coil is disposed under the reflector. Becauseof these arrangements, the strobe devices of Patent Literatures 1 and 2are far from being compact.

CITATION LIST Patent Literature

-   -   Patent Literature 1: Japanese Unexamined Patent Publication No.        H10-186466    -   Patent Literature 2: Japanese Unexamined Patent Publication No.        2004-334100

SUMMARY OF THE INVENTION

The present invention is directed to provide a strobe device includingthe following components: a flash discharge tube having an anode on oneside thereof and a cathode on the other side thereof; a conductivereflector composing a trigger external electrode, which is in in contactwith a part of the flash discharge tube and stores the part; a triggercoil having a hollow core, and a primary winding and a secondary windingwound around the core; and a conductor connecting the secondary windingof the trigger coil and the reflector. The trigger coil has an end ofthe flash discharge tube inserted into the core, and includes, at an endthereof adjacent to the reflector, a secondary terminal connected to thesecondary winding. The reflector has a bottom in contact with the outerperipheral surface of the flash discharge tube, the outer peripheralsurface covering at least the region extending from the anode to thecathode. The conductor has a first contact portion in contact with thesecondary terminal of the trigger coil, and a second contact portion incontact with the bottom of the reflector.

This configuration provides a compact and thin strobe device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a strobe device according to anexemplary embodiment of the present invention.

FIG. 2 is a sectional view of the strobe device according to theexemplary embodiment taken along line 2-2 of FIG. 1.

FIG. 3 is an exploded perspective view of the strobe device according tothe exemplary embodiment.

FIG. 4 is an exploded perspective view of an essential part of thestrobe device according to the exemplary embodiment.

FIG. 5A is a perspective view of the essential part of the strobe deviceaccording to the exemplary embodiment.

FIG. 5B is a front view of the essential part of the strobe deviceaccording to the exemplary embodiment.

FIG. 6A is a front view showing the arrangement of a flash dischargetube and a reflector of the strobe device according to the exemplaryembodiment.

FIG. 6B is a perspective view showing the arrangement of the flashdischarge tube and the reflector of the strobe device according to theexemplary embodiment.

FIG. 7A is a perspective view of a trigger coil of the strobe deviceaccording to the exemplary embodiment.

FIG. 7B is a perspective view of the trigger coil of the strobe deviceaccording to the exemplary embodiment viewed in a different direction.

DESCRIPTION OF EMBODIMENT

A strobe device according to an exemplary embodiment of the presentinvention will now be described with reference to drawings. Note thatthe present invention is not limited to the following exemplaryembodiment.

EXEMPLARY EMBODIMENT

The strobe device according to the exemplary embodiment of the presentinvention will now be described with reference to FIGS. 1 to 7B.

First, the schematic configuration of the strobe device of the exemplaryembodiment of the present invention will be described with reference toFIGS. 1 to 3.

FIG. 1 is a perspective view of the strobe device according to theexemplary embodiment. FIG. 2 is a sectional view of the strobe deviceaccording to the exemplary embodiment taken along line 2-2 of FIG. 1.FIG. 3 is an exploded perspective view of the strobe device according tothe exemplary embodiment.

As shown in FIG. 1, strobe device 1 of the exemplary embodiment includesbase 6, and optical panel 8 engaged with base 6. Strobe device 1 furtherincludes primary terminal 23 and common terminal 24 of a trigger coil(not shown), and anode terminal 32, all of which are external terminalsprojecting outside strobe device 1.

As shown in FIGS. 2 and 3, strobe device 1 of the exemplary embodimentstores at least flash discharge tube 2 for emitting light, conductivereflector 3, trigger coil 4, and conductor 5. Reflector 3 stores a partof flash discharge tube 2, thereby functioning as a trigger externalelectrode of flash discharge tube 2. Trigger coil 4 is disposed on otherside 2B of flash discharge tube 2 in such a manner that primary terminal23 and common terminal 24 project outside strobe device 1. Conductor 5electrically connects reflector 3 and trigger coil 4.

Base 6 is made of an insulating material such as polycarbonate. As shownin FIG. 3, base 6 includes holding portion 30 for holdingbelow-described second contact portion 28 of conductor 5 so as to storereflector 3. Base 6 also includes fixing part 7 for fixing one side 2Aof flash discharge tube 2 to base 6. Fixing part 7 has connectingportion 31 which is configured to be connected to anode 10 of flashdischarge tube 2, and plate-shaped anode terminal 32 which iselectrically connected to connecting portion 31 and is projecting as anexternal terminal. Connecting portion 31 is bonded by, for example,soldering to anode 10 of flash discharge tube 2.

Optical panel 8, which is made of a light transmitting material such asPMMA, covers reflector 3 so as to store it.

As shown in FIG. 2, flash discharge tube 2 includes tubular glass bulb9, anode 10 disposed on one side 2A, and cathode 11 disposed on otherside 2B. Glass bulb 9 is filled with a rare gas such as xenon at apredetermined pressure. When electrons collide with the rare gas, flashdischarge tube 2 generates and emits light to illuminate a subject.Anode 10 is a bar-shaped electrode made, for example, of tungsten. Anode10 is inserted into glass bulb 9 and fixed at one side 2A by beingmelted with glass beads (not shown). Cathode 11 is formed of bar-shapedelectrode 12 and metal sintered body 13. Bar-shaped electrode 12 ismade, for example, of tungsten, and is inserted into glass bulb 9 andfixed at other side 2B by being melted with glass beads (not shown).Metal sintered body 13 is made of a mixture of metal fine powder, suchas a mixture of tungsten and tantalum or a mixture of tantalum andnickel. Metal sintered body 13 is fixed to bar-shaped electrode 12 atthe end inside glass bulb 9.

The following is a detailed description, with reference to FIGS. 5A to7B, of the configuration of reflector 3 and trigger coil 4 of strobedevice 1 according to the exemplary embodiment.

FIG. 5A is a perspective view of the essential part of the strobe deviceaccording to the exemplary embodiment according to the exemplaryembodiment. FIG. 5B is a front view of the essential part of the strobedevice according to the exemplary embodiment. FIGS. 6A and 6B are afront view and a perspective view, respectively, showing the arrangementof the flash discharge tube and the reflector of the strobe deviceaccording to the exemplary embodiment. FIGS. 7A and 7B are perspectiveviews of the trigger coil of the strobe device viewed in differentdirections from each other according to the exemplary embodiment.

As shown in FIGS. 5A to 6B, reflector 3 has bottom 14, opening 15, sidereflective portion 16, and recessed installation portion 17. Bottom 14of reflector 3 is configured to be in contact with the outer peripheralsurface of flash discharge tube 2. This allows reflector 3 to functionas a trigger external electrode of flash discharge tube 2. Opening 15passes the light emitted from flash discharge tube 2 to the outside.Side reflective portion 16 reflects the light emitted from flashdischarge tube 2 toward opening 15. Installation portion 17 stores flashdischarge tube 2.

Bottom 14 of reflector 3 is formed of base portion 18 and extension 19.Base portion 18 is configured to be in contact with the outer peripheralsurface of flash discharge tube 2 so as to cover the region extendingfrom anode 10 to cathode 11. Base portion 18 has a shape of an archaving substantially (or exactly) the same radius as glass bulb 9 sothat base portion 18 can be in surface contact with the outer peripheralsurface of glass bulb 9. This configuration allows base portion 18 tofunction as a reflective plate for reflecting the light emitted fromflash discharge tube 2, and also as a trigger external electrode offlash discharge tube 2.

Extension 19 extends from base portion 18 of bottom 14 toward other side2B of flash discharge tube 2 in the axial (longitudinal) direction so asto be in contact with the outer peripheral surface of flash dischargetube 2, thereby covering metal sintered body 13 of cathode 11. Extension19 has a shape of an arc having substantially (or exactly) the sameradius as glass bulb 9 so as to be in surface contact with the outerperipheral surface of glass bulb 9. This configuration allows extension19 to function as a trigger external electrode of flash discharge tube 2in the same manner as base portion 18.

As shown in FIGS. 7A and 7B, trigger coil 4 includes hollow cylindricalcore 20, and primary winding 21 and secondary winding 22 wound aroundcore 20. Core 20 is formed of a magnetic body such as ferrite. As shownin FIG. 2, primary winding 21 is on the other side (on the primaryterminal 23 side) of core 20 of trigger coil 4, whereas secondarywinding 22 is on one side of core 20 of trigger coil 4, that is, on theside adjacent to reflector 3 opposite to core 20. One end 22A ofsecondary winding 22 is connected to other end 21B of primary winding21.

Trigger coil 4 further includes primary terminal 23 connected to one end21A of primary winding 21; common terminal 24 connected to other end 21Bof primary winding 21 and to one end 22A of secondary winding 22; andsecondary terminal 25 connected to other end 22B of secondary winding22. Common terminal 24 is electrically connected also to cathode 11 offlash discharge tube 2.

As best shown in FIGS. 1 and 5A, primary terminal 23 and common terminal24 of trigger coil 4 are bar-shaped, projecting to the outside and areconnected as external terminals to, for example, an external drivingcircuit (not shown). Secondary terminal 25, on the other hand, has anannular plate shape and is disposed at an end of trigger coil 4 (in theaxial direction of core 20), that is, the end adjacent to reflector 3 asshown in FIG. 7B.

As shown in FIG. 2, hollow core 20 has locking member 26 for positioningflash discharge tube 2 in the axial (longitudinal) direction. Lockingmember 26 projects inside in the radial direction of core 20, therebylocking the end of flash discharge tube 2 on other side 2B. In core 20,a portion of bar-shaped electrode 12 on other side 2B leading up tometal sintered body 13 of cathode 11 melted after being inserted intoglass bulb 9 on other side 2B of flash discharge tube 2 is inserteduntil reaching locking member 26. Thus, the portion of cathode 11 notincluding metal sintered body 13 can be surely inserted into core 20 oftrigger coil 4.

Next, the configuration of conductor 5 of strobe device 1 according tothe exemplary embodiment will now be described in detail based on FIG. 4with reference to FIGS. 2 and 5B.

FIG. 4 is an exploded perspective view of the essential part of thestrobe device according to the exemplary embodiment.

As shown in FIG. 4, conductor 5 includes first contact portion 27, andsecond contact portion 28 connected to first contact portion 27, both ofwhich are, for example, plate-shaped. First contact portion 27 isconfigured to be in contact with secondary terminal 25 of trigger coil4, whereas second contact portion 28 is configured to be in contact withbottom 14 of reflector 3. This configuration establishes an electricalconnection between secondary terminal 25 of trigger coil 4 and bottom 14of reflector 3 via conductor 5.

First contact portion 27 of conductor 5 has insertion portion 29 of, forexample, a substantial (or exact) U shape so as to pass flash dischargetube 2 through it and into trigger coil 4. First contact portion 27 ofconductor 5 has a curved shape such as an arc, and the convex portion ofthe curve is in contact with secondary terminal 25 of trigger coil 4.

Second contact portion 28 of conductor 5, on the other hand, has a beltshape extending in the axial (longitudinal) direction of flash dischargetube 2 and is curved like an arc protruding toward bottom 14 ofreflector 3.

As shown in FIG. 2, trigger coil 4 is inserted into other side 2B offlash discharge tube 2 through conductor 5, and flash discharge tube 2stored in reflector 3 is laid between base 6 and optical panel 8. As aresult, second contact portion 28 of conductor 5 elastically deformsbetween bottom 14 of reflector 3 and base 6. Because of the restoringforce (biasing force) due to the elastic deformation of second contactportion 28 of conductor 5, second contact portion 28 can be in contactwith bottom 14 of reflector 3, and flash discharge tube 2 and othercomponents can be held in base 6 and optical panel 8.

As described above, base 6 includes holding portion 30 for holdingsecond contact portion 28. Holding portion 30 sandwiches second contactportion 28 between bottom 14 of reflector 3 and itself.

The strobe device of the exemplary embodiment is configured as describedabove. The operation and action of strobe device 1 of the exemplaryembodiment will now be described as follows.

First, a driving voltage is applied from an external driving circuit(not shown) to anode 10 and cathode 11 of flash discharge tube 2 viaanode terminal 32 and common terminal 24, which are external terminalsof strobe device 1.

At the same time as the application of the voltage or after apredetermined amount of time, a pulse-like voltage is applied from theexternal driving circuit (not shown) to primary winding 21 of triggercoil 4 via primary terminal 23 and common terminal 24, which areexternal terminals of strobe device 1. The voltage applied to primarywinding 21 is, for example, boosted at secondary winding 22. The boostedvoltage is applied as a trigger pulse to bottom 14 of reflector 3 fromsecondary terminal 25 of trigger coil 4 via first and second contactportions 27 and 28 of conductor 5.

This activates and ionizes the rare gas filled in glass bulb 9 near theinner periphery of glass bulb 9 which is in contact with base portion 18and extension 19 of bottom 14 of reflector 3.

Cathode 11 also emits electrons toward anode 10 so as to promote theionization of the rare gas, making the rare gas more conductive. Thiscauses a sudden large current flow from anode 10 to cathode 11, allowingflash discharge tube 2 to emit light to illuminate the outside.

At this moment, the trigger pulse is applied also to extension 19 ofbottom 14 of reflector 3 covering metal sintered body 13 of cathode 11.The pulse application allows electrons emitted from cathode 11 to stablyform a discharge path starting from the vicinity of cathode 11. Thisreduces variations in the amount of light emitted from flash dischargetube 2, thereby irradiating the subject in a stable manner.

The present invention is not limited to the above-described exemplaryembodiment and can be properly changed within the range not deviatingfrom the spirit of the present invention. It also goes without sayingthat the configuration and methods of the following various modifiedexamples can be arbitrary selected and adopted into the above-describedexemplary embodiment.

For example, flash discharge tube 2 has no thin-film transparentelectrode on its surface in the exemplary embodiment, but mayalternatively have a thin-film transparent electrode such as an ITO orNESA film formed thereon. In this case, too, at least the regionextending from anode 10 to cathode 11 of flash discharge tube 2, andmetal sintered body 13 can be covered by bottom 14 of reflector 3, whichis in contact with the outer peripheral surface of the glass bulb offlash discharge tube 2 having the thin-film transparent electrode formedthereon. This reduces variations in the amount of light emitted fromflash discharge tube 2, thereby irradiating the subject in a stablemanner.

Extension 19 of reflector 3 is arc-shaped in the exemplary embodiment,but may alternatively be, for example, flat-shaped. In this case, too,the discharge path of the electrons emitted from cathode 11 can beformed stably from the vicinity of cathode 11.

First contact portion 27 of conductor 5 is a substantial U shape withinsertion portion 29 inside in the exemplary embodiment, but mayalternatively be, for example, a ring shape, that is, a substantial (orexact) O shape with insertion portion 29 as an opening in the center.This improves the accuracy of positioning first contact portion 27relative to flash discharge tube 2.

Second contact portion 28 of conductor 5 is curved like an arc in thelongitudinal direction in the exemplary embodiment, but mayalternatively have, for example, a plurality of peaks and troughs in thelongitudinal direction, that is, corrugated. This configuration improvesthe contact between bottom 14 of reflector 3 and glass bulb 9 of flashdischarge tube 2.

As described hereinbefore, strobe device 1 of the present inventionincludes flash discharge tube 2 having anode 10 on one side thereof andcathode 11 on the other side thereof; conductive reflector 3 composing atrigger external electrode, which is in contact with a part of flashdischarge tube 2 and stores the part; trigger coil 4 having hollow core20, and primary winding 21 and secondary winding 22 wound around core20; and conductor 5 connecting secondary winding 22 of trigger coil 4and reflector 3. Trigger coil 4 has an end of flash discharge tube 2inserted into core 20, and includes, at an end thereof adjacent toreflector 3, secondary terminal 25 connected to secondary winding 22.Reflector 3 has bottom 14 in contact with the outer peripheral surfaceof flash discharge tube 2, the outer peripheral surface covering atleast the region extending from anode 10 to cathode 11. Conductor 5 hasfirst contact portion 27 in contact with secondary terminal 25 oftrigger coil 4, and second contact portion 28 in contact with bottom 14of reflector 3.

In this configuration, the end of flash discharge tube 2 is insertedinto core 20 of trigger coil 4, and secondary terminal 25 electricallyconnected to secondary winding 22 is disposed at that end, which isadjacent to reflector 3, of trigger coil 4. This configuration allowsstrobe device 1 to be compact and thin.

Bottom 14 of reflector 3 is in contact with the outer peripheral surfaceof flash discharge tube 2 so as to cover at least the region extendingfrom anode 10 to cathode 11 of flash discharge tube 2. First contactportion 27 of conductor 5 is in contact with secondary terminal 25 oftrigger coil 4. Second contact portion 28 of conductor 5 connected tofirst contact portion 27 elastically deforms and holds bottom 14 ofreflector 3 and flash discharge tube 2 in such a manner that reflector 3and flash discharge tube 2 are in contact with each other. This ensuresthe electrical connection between secondary terminal 25 of trigger coil4 and bottom 14 of reflector 3 via conductor 5. This also greatlyreduces the connection distance between flash discharge tube 2 andsecondary terminal 25, which outputs a trigger pulse. This configurationeliminates the power loss caused by the resistance of a lead wire usedfor connection as in the conventional strobe devices.

In strobe device 1 of the present invention, first contact portion 27 ofconductor 5 includes insertion portion 29 into which flash dischargetube 2 is inserted, and second contact portion 28 of conductor 5 has acurved belt shape extending in the longitudinal direction of flashdischarge tube 2.

In this configuration, flash discharge tube 2 is inserted into insertionportion 29 formed in first contact portion 27 of conductor 5, therebyallowing first contact portion 27 to be positioned relative to flashdischarge tube 2. Furthermore, second contact portion 28 of conductor 5is shaped like a belt extending along flash discharge tube 2 and is alsocurved in the longitudinal direction of flash discharge tube 2. As aresult, second contact portion 28 of conductor 5 can elastically deform,allowing bottom 14 of reflector 3 to be held in contact with flashdischarge tube 2.

In strobe device 1 of the present invention, cathode 11 of flashdischarge tube 2 includes metal sintered body 13 at an end thereof.

In strobe device 1 of the present invention, flash discharge tube 2 isinserted at a portion thereof into core 20 of trigger coil 4, theportion being on the cathode 11 side of flash discharge tube 2 and notincluding metal sintered body 13.

In the strobe device of the present invention, bottom 14 of reflector 3is disposed to further cover metal sintered body 13 of flash dischargetube 2.

Thus, metal sintered body 13 is formed at an end of cathode 11, and theportion of flash discharge tube 2 which does not contain metal sinteredbody 13 is inserted into core 20 of trigger coil 4. This configurationallows strobe device 1 to be compact and thin.

When a voltage is applied between anode 10 and cathode 11 of flashdischarge tube 2, and a trigger pulse is applied to bottom 14 ofreflector 3, a uniform electron flow is generated between anode 10 andcathode 11 of flash discharge tube 2. In this case, bottom 14 ofreflector 3 which is in contact with the outer peripheral surface offlash discharge tube 2 covers not only the region extending from anode10 to cathode 11, but also metal sintered body 13 of cathode 11. In thiscase, the discharge path of the electrons emitted from cathode 11 can beformed stably from the vicinity of cathode 11. This reduces variationsin the amount of light emitted from flash discharge tube 2, therebyirradiating the subject in a stable manner.

INDUSTRIAL APPLICABILITY

The compact strobe device of the present invention is useful forirradiating a subject to take pictures of.

REFERENCE MARKS IN THE DRAWINGS

-   1 strobe device-   2 flash discharge tube-   2A one side-   2B other side-   3 reflector-   4 trigger coil-   5 conductor-   6 base-   7 fixing part-   8 optical panel-   9 glass bulb-   10 anode-   11 cathode-   12 bar-shaped electrode-   13 metal sintered body-   14 bottom-   15 opening-   16 side reflective portion-   17 installation portion-   18 base portion-   19 extension-   20 core-   21 primary winding-   21A, 22A one end-   21B, 22B other end-   22 secondary winding-   23 primary terminal-   24 common terminal-   25 secondary terminal-   26 locking member-   27 first contact portion-   28 second contact portion-   29 insertion portion-   30 holding portion-   31 connecting portion-   32 anode terminal

1. A strobe device comprising: a flash discharge tube having an anode onone side thereof and a cathode on an other side thereof; a conductivereflector composing a trigger external electrode, the trigger externalelectrode being in contact with a part of the flash discharge tube andstoring the part; a trigger coil having a hollow core, and a primarywinding and a secondary winding wound around the core; and a conductorconnecting the secondary winding of the trigger coil and the reflector,wherein the trigger coil has an end of the flash discharge tube insertedinto the core, and includes, at an end thereof adjacent to thereflector, a secondary terminal connected to the secondary winding; thereflector has a bottom in contact with an outer peripheral surface ofthe flash discharge tube, the outer peripheral surface covering at leasta region extending from the anode to the cathode; and the conductor hasa first contact portion in contact with the secondary terminal of thetrigger coil, and a second contact portion in contact with the bottom ofthe reflector.
 2. The strobe device of claim 1, wherein the firstcontact portion of the conductor includes an insertion portion intowhich the flash discharge tube is inserted; and the second contactportion of the conductor has a curved belt shape extending in alongitudinal direction of the flash discharge tube.
 3. The strobe deviceof claim 1, wherein the cathode of the flash discharge tube includes ametal sintered body at an end thereof.
 4. The strobe device of claim 3,wherein the flash discharge tube is inserted at a portion thereof intothe core of the trigger coil, the portion being on the cathode side ofthe flash discharge tube and not including the metal sintered body. 5.The strobe device of claim 3, wherein the bottom of the reflector isdisposed to further cover the metal sintered body of the flash dischargetube.